Bongo Fury

So, when it's cold my Bongo makes a bit of a squeeky belt sound.

I'm not sure which belt it is, is there a usual culprit on Bongos? (2.0 Petrol, 2006)
Should I be worried about anything, does it need taking to a garage?

Timing belt was changed 2 years and 12,000 miles ago so shouldn't need doing again for a while.
What else can I check/do?

Thanks,
Pete

There are only two belts so maybe squirting some water on each in turn would identify which one is the cause ?

The diesel have adjustable tension wheel / pulleys on them
To tighten a slipping belt
I'd imaging the petrol models do as well
Only a 5 min job to tighten them up a bit
But might be a good time to replace belts